A concrete pool shell is the one part of your new pool you will never see again once the finish goes on top of it. Get the sequence right — marking out, excavation, steel, pour, fittings, cure — and the shell holds its shape for decades under whichever finish you choose later. Rush or reorder any one of those steps, and the problems surface years afterward, long after crews have paved the site and moved on. This article walks through that sequence in the order our crews actually follow it on a Gauteng site, and shows where in that sequence the decisions that matter most actually happen.
Marking out and excavation decide the shape you live with
Every build starts with marking out and squaring the site, before a TLB or a single spade goes in. Squaring sounds like a formality, but a pool that sits even 20mm out of square at this stage throws the coping line, the apron width, and the fitting positions off by the time you reach the finish. Once the shell cures, that misalignment is permanent.
Excavation itself happens by hand, by TLB, or a mix of both, depending on access and the space available on site. A freestanding property with a driveway wide enough for machinery lets a TLB do most of the digging, which is faster and cheaper. A tighter site, boxed in by walls or a narrow side gate, pushes more of the dig onto hand labour, which takes longer even when the pool itself is small. Either way, excavation follows the marked-out shape exactly — nobody adjusts the hole later to fit the steel.
The skeleton and the mass behind the shape
Once the hole matches the plan, the steel goes in. We tie Y8 steel bars and 100mm mesh wire into a ring beam that runs around the full perimeter of the shape, then pour 30 MPa ready-mix concrete over it to a thickness of 150mm across the floor and walls. We have set out why those exact numbers matter elsewhere in detail — the short version is that the steel stops the shell cracking under water pressure and ground movement, and the concrete grade gives it the mass to hold its shape through Gauteng’s clay soils. What matters here is simpler: none of it is negotiable, and none of it is visible again once the pour is complete.
Fittings that go in before the concrete sets
The weir, the aim-flow fitting and the LED light all go into position while the concrete is still wet, not after the shell has cured. This is a deliberate sequencing choice, not a shortcut. A fitting pushed into curing concrete bonds directly into the structure of the shell, rather than sitting in a hole cut into hardened concrete and sealed around the edges afterward.
The difference shows up at the fitting line years later. A fitting bonded into the pour moves with the shell as one piece. A fitting retrofitted into an already-cured shell relies on the seal around it holding for the life of the pool, and seals are exactly the kind of detail that fails quietly, drop by drop, long before anyone notices.
Curing time is not downtime
After the pour, the shell sits for three to five days before anyone touches it again. Concrete gains strength as it cures, and shortening that window to save a day on the programme is one of the more common shortcuts in pool building. You cannot see the difference on handover day. You see it years later, as hairline cracking that widens with every season.
Temperature changes how that curing period behaves. Warmer months let concrete cure faster and more predictably. Colder Gauteng mornings slow the chemical reaction that gives concrete its strength, which is one reason a pour scheduled through winter needs to plan the cure window around the weather rather than the calendar. Either way, nobody starts finish work — marbelite, fibreglass, or anything else — until that window has run its full course.
Council sign-off happens before the shell, not after
Before excavation starts, council typically wants approved drawings and a signed indemnity form on file. This applies whether you are building a new pool or adding a barrier to an existing one, and it is a step homeowners often assume happens somewhere in the background without their input.
We handle that administration as part of the build rather than leaving you to chase it between departments. It sits ahead of excavation for a reason: council does not want a hole in the ground before the paperwork explains what it is for, and neither will you if you ever sell the property and an attorney asks for proof the pool was approved.
A stage-by-stage look at the concrete pool shell
Laid out in order, the sequence looks simpler than it feels on site, where weather, access and site conditions all push against the schedule. The table below shows what happens at each stage and why the order cannot be shuffled to save time.
| Stage | What happens | Why the order matters |
|---|---|---|
| Marking out & squaring | Site measured and pegged to the exact pool shape | Errors here shift coping, paving and fittings later |
| Excavation | Hand digging and/or TLB, depending on access | Access, not pool size alone, determines time and cost |
| Steel fixing | Y8 bars, 100mm mesh wire, ring beam tied in | Gives the shell its skeleton before concrete arrives |
| Concrete pour | 30 MPa ready-mix poured to 150mm | Grade and thickness give the shell its mass and strength |
| Fitting placement | Weir, aim-flow and LED positioned in wet concrete | Bonds fittings into the structure instead of sealing them in afterward |
| Curing | Three to five days before further work begins | Concrete needs this time to reach its rated strength |
| Finish decision | Marbelite or fibreglass applied once cured | An independent choice, made only once the shell is proven sound |
Add it up, and a new shell typically moves from marking out to a cured, finish-ready structure well inside the first stretch of a build that runs two to three weeks in total, from breaking ground to a filled and commissioned pool.
What to ask before the shell gets poured
You cannot inspect a concrete pool shell once it is finished — the steel, the ring beam, the concrete grade all disappear under the finish coat. That makes the questions you ask before the pour more useful than any inspection you could carry out afterward.
Ask which steel and mesh size the contractor uses, and ask for the concrete grade and pour thickness in writing on the quote, not just described verbally on site. Ask whether excavation will run by hand, by TLB, or both, given your specific access — a vague answer here usually means nobody has actually walked your site yet. Ask, too, what happens if a problem shows up in the shell later.
That last question is worth pressing on, because the answer tells you how much confidence a contractor has in their own work. Our own shells carry a ten-year structural guarantee, separate from the warranty on the finish that goes on top. It holds for anything short of storm damage or someone interfering with the work while it is still curing — the kind of assurance that only makes sense once you have poured enough shells to trust your own steel and concrete.
Frequently asked questions
Why is marking out and squaring the site so important before excavation?
A pool that isn’t perfectly square from the start can lead to misaligned coping, apron width, and fitting positions by the time the finish is applied. Once the shell cures, any misalignment becomes permanent.
How does the steel reinforcement contribute to the pool shell's integrity?
The steel bars and mesh are tied into a ring beam and form the skeleton of the shell. This structure prevents the shell from cracking due to water pressure and ground movement, ensuring its long-term stability.
Why are fittings like the weir, aim-flow, and lights installed while the concrete is still wet?
Installing fittings in wet concrete bonds them directly into the shell’s structure. This is preferable to cutting holes in hardened concrete and sealing afterward, as it creates a more durable, unified piece that moves with the shell.
What is the purpose of the curing period after the concrete pour?
The shell needs three to five days to cure, during which the concrete gains strength. Skipping this period to save time can lead to hairline cracks that widen over time, compromising the shell’s integrity.
When does council approval typically happen in the pool construction process?
Council approval, including approved drawings and a signed indemnity form, is usually required before excavation begins. This ensures that the project is properly documented and authorized from the outset.
What questions should I ask a contractor before the concrete shell is poured?
You should ask about the specific steel and mesh sizes used, the concrete grade and pour thickness (in writing), and the excavation method planned for your site’s access. Also, inquire about their policy for addressing any shell issues that arise later.
Ready to take the next step?
If this is what you are looking for, get in touch and we will help you get started.